[after the IBM System/360 Reference Data
card] A summary of an assembly language, even if the color is not green and
not a card. Less frequently used now because of the decrease in the use of
assembly language. “I'll go get my green card so I can check the
addressing mode for that instruction.”

The original green card became a yellow card when the System/370 was
introduced, and later a yellow booklet. An anecdote from IBM refers to a
scene that took place in a programmers' terminal room at Yorktown in 1978.
A luser overheard one of the programmers ask another
“Do you have a green card?” The other grunted and passed the
first a thick yellow booklet. At this point the luser turned a delicate
shade of olive and rapidly left the room, never to return.

In fall 2000 it was reported from Electronic Data Systems that the
green card for 370 machines has been a blue-green booklet since
1989.